Write a shell script to append "snork" to the file "test" but only if "test" already exists.

Code:
[ -f test ] && echo "snork" >> test ||:
* A user performed a `cd; chmod 644 .` before logging out. What problem occurs when he logs in the next time, and what level of privilege is required to correct the problem?
User will not able to login. A root user can this problem by resting permission
cmod perm /home/user
. is current directory
.. parent directory